The production and perception of peripheral geminate/singleton coronal stop contrasts in Arabic

Gemination is typologically common word-medially but is rare at the periphery of the word (word-initially and -finally). In line with this observation, prior research on production and perception of gemination has focused primarily on medial gemination. Much less is known about the production and perception of peripheral gemination. This PhD thesis reports on comprehensive articulatory, acoustic and perceptual investigations of geminate-singleton contrasts according to the position of the contrast in the word and in the utterance. The production component of the project investigated the articulatory and acoustic features of medial and peripheral gemination of voiced and voiceless coronal stops in Modern standard Arabic and regional Arabic vernacular dialects, as produced by speakers from two disparate and geographically distant countries, Morocco and Lebanon. The perceptual experiment investigated how standard and dialectal Arabic gemination contrasts in each word position were categorised and discriminated by three groups of non-native listeners, each differing in their native language experience with gemination at different word positions. The first experiment used ultrasound and acoustic recordings to address the extent to which word-initial gemination in Moroccan and Lebanese dialectal Arabic is maintained, as well as the articulatory and acoustic variability of the contrast according to the position of the gemination contrast in the utterance (initial vs. medial) and between the two dialects. The second experiment compared the production of word-medial and -final gemination in Modern Standard Arabic as produced by Moroccan and Lebanese speakers. The aim of the perceptual experiment was to disentangle the contribution of phonological and phonetic effects of the listeners’ native languages on the categorisation and discrimination of non-lexical Moroccan gemination by three groups of non-native listeners varying in their phonological (native Lebanese group and heritage Lebanese group, for whom Moroccan is unintelligible, i.e., non-native language) and phonetic-only (native English group) experience with gemination across the three word positions. The findings in this thesis constitute important contributions about positional and dialectal effects on the production and perception of gemination contrasts, going beyond medial gemination (which was mainly included as control) and illuminating in particular the typologically rare peripheral gemination

Immediate and Distracted Imitation in Second-Language Speech: Unreleased Plosives in English

The paper investigates immediate and distracted imitation in second-language speech using unreleased plosives. Unreleased plosives are fairly frequently found in English sequences of two stops. Polish, on the other hand, is characterised by a significant rate of releases in such sequences. This cross-linguistic difference served as material to look into how and to what extent non-native properties of sounds can be produced in immediate and distracted imitation. Thirteen native speakers of Polish first read and then imitated sequences of words with two stops straddling the word boundary. Stimuli for imitation had no release of the first stop. The results revealed that (1) a non-native feature such as the lack of the release burst can be imitated; (2) distracting imitation impedes imitative performance; (3) the type of a sequence interacts with the magnitude of an imitative effec

Perceptual Asymmetry and Sound Change: An Articulatory, Acoustic/Perceptual, and Computational Analysis

Previous experimental study of the identification of stop and fricative consonants has shown that some consonant pairs are asymmetrically confused for one another, with listeners’ percepts tending to favor one member of the pair in a conditioning context. Researchers have also suggested that this phenomenon may play a conditioning role in sound change, although the mechanism by which perceptual asymmetry facilitates language change is somewhat unclear. This dissertation uses articulatory, acoustic, and perceptual data to provide insight on why perceptual asymmetry is observed among certain consonants and in specific contexts. It also uses computational modeling to generate initial predictions about the contexts in which perceptual asymmetry could contribute to stability or change in phonetic categories. Six experiments were conducted, each addressing asymmetry in the consonant pairs /k/-/t/ (before /i/), /k/-/p/ (before /i u/), /p/-/t/ (before /i/), and /θ/-/f/ (possibly unconditioned). In the articulatory experiment, vocal tract spatial parameters were extracted from real-time MRI video of speakers producing VCV disyllables in order to address the role of vocal tract shape in the target consonants’ vowel-dependent spectral similarity. The results suggest that, for consonant pairs involving /k/, CV coarticulation creates—as expected—vocal tract shapes that are most similar to one another in the environment conditioning perceptual asymmetry. However, CV coarticulation was less informative for explaining the vocalic conditioning of the /p/-/t/ asymmetry. In the second experiment, RF models were trained on acoustic samples of the target consonants from a speech corpus. Their output, which was used to identify frequency components important to the discrimination of consonant pairs, aligned well with these consonants’ spectral characteristics as predicted by acoustic models. A follow-up perception experiment that examined the categorization strategies of participants listening to band-filtered CV syllables generally showed listener sensitivity to these same components, although listeners were also sensitive to band-filtering outside the predicted frequency bands. Perceptual asymmetry is observed in CV and isolated C contexts. In the fourth experiment, a Bayesian analysis was performed to help explain why perceptual asymmetry appears when listening to isolated Cs, and a follow-up perception experiment helped to evaluate the relevance of this analysis to human perception. For /k/-/t/, for example, whose confusions favor /t/, this analysis suggested that [t] and [k] both have the highest likelihood of being generated by /t/ (relative to likelihood of /k/ generating each) in the context conditioning asymmetry. The follow-up study suggests listeners are more likely to categorize a [t] and [k] as /t/ if it has higher likelihood of being generated by /t/ (relative to /k/). The final experiment used agent-based modeling to simulate the intergenerational transmission of phonetic categories. Its results suggest that perceptual asymmetry can affect the acquisition of categories under certain conditions. A lack of reliable access to non-phonetic information about the speaker’s intended category or a tendency not to store tokens with low discriminability can both contribute to the instability of phonetic categories over time, but primarily in the contexts conditioning asymmetry. This dissertation makes several contributions to research on perceptual asymmetry. The articulatory experiment suggests that confusability can be mirrored by gestural ambiguity. The Bayesian analysis could also be used to build and test predictions about the confusability of other sounds by context. Finally, the model simulations offer predictions of the conditions where perceptual asymmetry could condition sound change.PHDLinguisticsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/155085/1/iccallow_1.pd

Sociololinguistic competence and the bilingual's adoption of phonetic variants: auditory and instrumental data from English-Arabic bilinguals

This study is an auditory and acoustic investigation of the speech production patterns developed by English-Arabic bilingual children. The subjects are three Lebanese children aged five, seven and ten, all born and raised in Yorkshire, England. Monolingual friends of the same age were chosen as controls, and the parents of all bilingual and monolingual children were also taped to obtain a detailed assessment of the sound patterns available in the subjects' environment. The study addresses the question of interaction between the bilingual's phonological systems by calling for a refinement of the notion of a `phonological system' using insights from recent phonetic and sociolinguistic work on variability in speech (e. g. Docherty, Foulkes, Tillotson, & Watt, 2002; Docherty & Foulkes, 2000; Local, 1983; Pisoni, 1997; Roberts, 1997; Scobbie, 2002). The variables under study include /1/, In, and VOT production. These were chosen due to the existence of different patterns in their production in English and Arabic that vary according to contextual and dialectal factors. Data were collected using a variety of picture-naming, story-telling, and free-play activities for the children, and reading lists, story-telling, and interviews for the adults. To control for language mode (Grosjean, 1998), the bilinguals were recorded in different language sessions with different interviewers. Results for the monolingual children and adults in this study underline the importance of including controls in any study of bilingual speech development for a better interpretation of the bilinguals' patterns. Input from the adults proved highly variable and at times conflicted with published patterns normally found in the literature for the variables under study. Results for the bilinguals show that they have developed separate sociolinguistically-appropriate production patterns for each of their languages that are on the whole similar to those of monolinguals but that also reflect the bilinguals' rich socio-phonetic repertoire. The interaction between the bilinguals' languages is mainly restricted to the bilingual mode and is a sign of their developing sociolinguistic competence

Learning [Voice]

The [voice] distinction between homorganic stops and fricatives is made by a number of acoustic correlates including voicing, segment duration, and preceding vowel duration. The present work looks at [voice] from a number of multidimensional perspectives. This dissertation\u27s focus is a corpus study of the phonetic realization of [voice] in two English-learning infants aged 1;1--3;5. While preceding vowel duration has been studied before in infants, the other correlates of post-vocalic voicing investigated here --- preceding F1, consonant duration, and closure voicing intensity --- had not been measured before in infant speech. The study makes empirical contributions regarding the development of the production of [voice] in infants, not just from a surface-level perspective but also with implications for the phonetics-phonology interface in the adult and developing linguistic systems. Additionally, several methodological contributions will be made in the use of large sized corpora and data modeling techniques. The study revealed that even in infants, F1 at the midpoint of a vowel preceding a voiced consonant was lower by roughly 50 Hz compared to a vowel before a voiceless consonant, which is in line with the effect found in adults. But while the effect has been considered most likely to be a physiological and nonlinguistic phenomenon in adults, it actually appeared to be correlated in the wrong direction with other aspects of [voice] here, casting doubt on a physiological explanation. Some of the consonant pairs had statistically significant differences in duration and closure voicing. Additionally, a preceding vowel duration difference was found and as well a preliminary indication of a developmental trend that suggests the preceding vowel duration difference is being learned. The phonetics of adult speech is also considered. Results are presented from a dialectal corpus study of North American English and a lab speech experiment which clarifies the relationship between preceding vowel duration and flapping and the relationship between [voice] and F1 in preceding vowels. Fluent adult speech is also described and machine learning algorithms are applied to learning the [voice] distinction using multidimensional acoustic input plus some lexical knowledge

Asymmetric discrimination of non-speech tonal analogues of vowels

Published in final edited form as: J Exp Psychol Hum Percept Perform. 2019 February ; 45(2): 285–300. doi:10.1037/xhp0000603.Directional asymmetries reveal a universal bias in vowel perception favoring extreme vocalic articulations, which lead to acoustic vowel signals with dynamic formant trajectories and well-defined spectral prominences due to the convergence of adjacent formants. The present experiments investigated whether this bias reflects speech-specific processes or general properties of spectral processing in the auditory system. Toward this end, we examined whether analogous asymmetries in perception arise with non-speech tonal analogues that approximate some of the dynamic and static spectral characteristics of naturally-produced /u/ vowels executed with more versus less extreme lip gestures. We found a qualitatively similar but weaker directional effect with two-component tones varying in both the dynamic changes and proximity of their spectral energies. In subsequent experiments, we pinned down the phenomenon using tones that varied in one or both of these two acoustic characteristics. We found comparable asymmetries with tones that differed exclusively in their spectral dynamics, and no asymmetries with tones that differed exclusively in their spectral proximity or both spectral features. We interpret these findings as evidence that dynamic spectral changes are a critical cue for eliciting asymmetries in non-speech tone perception, but that the potential contribution of general auditory processes to asymmetries in vowel perception is limited.Accepted manuscrip

Consonantal voicing effects on vowel duration in Italian-English bilinguals

This project reported in this dissertation analyzes phonetic details of the speech patterns in one of New York\u27s bilingual communities, asking whether a bilingual speaker can attain native-like proficiency in both languages and the extent to which authenticity — maintenance of language-specific settings — is sustainable. Researchers have established that Italian and English differ strikingly in their characteristic time settings for vowel durations: durations are greater for vowels preceding voiced consonants, e.g., cab, rather than voiceless, e.g., cap. This duration difference, termed the consonantal voicing effect (CVE), is notably greater for English than for Italian. The greater magnitude of the CVE found with English is considered to be a phonological enhancement of a basic phonetic process. Utilizing a speech production task, the study reported compares the performance of Italian-born bilinguals for whom English was acquired in adulthood, as a second language, with that of U.S.-born speakers who experienced simultaneous acquisition of their languages (albeit in an English-dominant setting). In separate sessions for each language, speakers produced utterances in which the target word, situated inside a carrier phrase, contrasted in [voice] value for the post-vocalic consonant, e.g., Say the word « ___ » to me. Stimuli were familiar words selected to sample the vowel inventories for each language and for which the voicing contrast was realized through the inventory of stops common to both languages. Analyses revealed no evidence of influence of the second language on the CVE for the first language for either group, despite an extended immersion period in an English-language environment for the foreign-born speakers and simultaneous exposure to both languages from birth for the U.S.-born speakers. But crucially, there was evidence of an influence of the first language in the timing settings found for the CVE in the second language, for both speaker groups: the foreign-born speakers managed to increase the magnitude of the CVE-English but failed to fully implement the phonological mechanism consistent with larger CVE values for that language; and the U.S.-born speakers managed to reduce the magnitude of the CVE-Italian but failed to fully suppress that same mechanism. Results are discussed in relation to language-specific timing patterns and the extent to which a dominant language may influence production in the non-dominant language

Voice and Emphasis in Arabic Coronal Stops: Evidence for Phonological Compensation

The current study investigates multiple acoustic cues–voice onset time (VOT), spectral center of gravity (SCG) of burst, pitch (F0), and frequencies of the first (F1) and second (F2) formants at vowel onset—associated with phonological contrasts of voicing and emphasis in production of Arabic coronal stops. The analysis of the acoustic data collected from eight native speakers of the Qatari dialect showed that the three stops form three distinct modes on the VOT scale: [d] is (pre)voiced, voiceless [t] is aspirated, and emphatic [ṭ] is voiceless unaspirated. The contrast is also maintained in spectral cues. Each cue influences production of coronal stops while their relevance to phonological contrasts varies. VOT was most relevant for voicing, but F2 was mostly associated with emphasis. The perception experiment revealed that listeners were able to categorize ambiguous tokens correctly and compensate for phonological contrasts. The listeners’ results were used to evaluate three categorization models to predict the intended category of a coronal stop: a model with unweighted and unadjusted cues, a model with weighted cues compensating for phonetic context, and a model with weighted cues compensating for the voicing and emphasis contrasts. The findings suggest that the model with phonological compensation performed most similar to human listeners both in terms of accuracy rate and error pattern